The present invention relates to field-effect type semiconductor devices and more particularly to a technique effectively applicable to a field-effect type semiconductor device for high-frequency power amplification of not less than 800 MHz used in a mobile communication unit.
With widespread use of a mobile communication terminal in recent years, a power amplifier for portable terminal of lower power consumption and higher efficiency has been demanded increasingly. For a power amplification device directed to this utilization, a transistor (HBT) using a compound semiconductor (HBT) or an insulated gate field-effect transistor (Si-MOSFET) using a silicon semiconductor (Si) has been used.
A power amplifier using the compound semiconductor is described in, for example, IEEE Journal of Solid-state Circuits, Volume:35 Issue: 8, pp. 1109–1120 (2000) (reference 1).
On the other hand, a power amplifier using the Si-MOSFET is detailed in, for example, IEDM99 Technical Digest (1999), pp. 205–208 (reference 2) or US 2001/0012671 A1 (reference 3).
Incidentally, a phenomenon that the mobility can be increased by using strained Si or SiGe alloy is indicated in J. Appl. Phys. 80 (1996), pp. 2234–2252 (reference 4), for instance.
Further, a method of promoting the performance of a transistor (MOSFET) in an IC (specifically, CMOSIC) by using this phenomenon is disclosed in, for example, JP-A-10-270685 (reference 5) or US 2001/0003364 A1 (reference 6).
In the technique described in reference 5, for the purpose of obtaining characteristics of such high performance as having high transconductance in low voltage operation, an nMOS transistor and a pMOS transistor, each having a LDD structure, are formed in a silicon layer in which strain is applied (the so-called strained Si layer).
Also, in the technique described in reference 6, for the purpose of obtaining a complementary field-effect transistor capable of operating at a high speed and reducing power consumption, an nMOS transistor is formed in a strained silicon layer and a pMOS transistor is formed in a strained silicon/germanium layer.